Priority is claimed to Japanese Patent Application No. JP2004-162657 filed on May 31, 2004, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a circuit device and a manufacturing method thereof, and more particularly relates to a circuit device including a plurality of wiring layers laminated with an insulating layer interposed therebetween, and a manufacturing method thereof.
2. Description of the Related Art
With reference to FIGS. 15A and 15B, a description will be given of a configuration of a conventional hybrid integrated circuit device 100. This technology is described for instance in Japanese Patent Application Publication No. Hei 6 (1994)-177295. FIG. 15A is a perspective view of the hybrid integrated circuit device 100, and FIG. 15B is a cross-sectional view along the line X-X′ in FIG. 15A.
The conventional hybrid integrated circuit device 100 includes a rectangular substrate 106, and an insulating layer 107 provided on a surface of the substrate 106. On the insulating layer 107, a wiring layer 108 is patterned. Furthermore, a circuit element 104 is fixed on the wiring layer 108, and the circuit element 104 and the wiring layer 108 are electrically connected to each other by use of a thin metal wire 105. A lead 101 electrically connected to the wiring layer 108 is drawn out to the outside. Moreover, the entire hybrid integrated circuit device 100 is sealed with a sealing resin 102. As a method for sealing the device with the sealing resin 102, there are injection molding using a thermoplastic resin, and transfer molding using a thermosetting resin.
However, in the hybrid integrated circuit device 100 described above, formation of a single layer of wiring leads to a problem that limits a size of an electric circuit that can be integrated. As one of methods for solving this problem, there is a method for forming a multilayer structure of wirings laminated with an insulating layer interposed therebetween. To be more specific, a multilayer wiring structure is formed by laminating more than two wiring layers with an insulating layer interposed therebetween.
In order to form the multilayer wiring structure described above, it is required to form a connection part which penetrates the insulating layer and connects the respective wiring layers to each other. However, large amounts of inorganic fillers are mixed in the insulating layer for improvement in heat release properties. Therefore, if a through-hole is formed in the insulating layer by use of a laser, the inorganic fillers are exposed to a sidewall of the through-hole to form irregularities. Since it is difficult to form a plated film on the through-hole in such a state, there is a problem that it is not easy to form the connection part described above.